DE 10 2008 049 005 A1 discloses a variable turbine geometry of the type in question with guide blades which are mounted rotatably in a blade carrier, wherein an adjusting ring is provided for adjusting the guide blades. Said adjusting ring is provided here with at least one contour which engages in at least one recess on the guide-blade-carrier side or bearing-housing side, wherein the contour and the recess interact with each other in such a manner that an adjusting movement of the adjusting ring relative to the blade carrier is limited.
US 2015/0292350 A1 discloses a further variable turbine geometry in which a certain position of the guide blades is likewise fixed via a corresponding stop geometry.
In general, what is referred to as a “maximum flow position” has to be defined in exhaust gas turbochargers, for example by means of a stop, in order in the most unfavourable case to prevent the guide blades of a variable turbine geometry from opening to such an extent that said guide blades pass into a turbine wheel and can thereby lead to failure of the exhaust gas turbocharger. This is customarily realized via a stop, formed by means of a pin or a grooved drive stud, in the bearing housing or in the blade carrier of the exhaust gas turbocharger, said stop blocking an articulated lever of the variable turbine geometry in its movement when the maximum flow position is reached and, via the adjusting ring, preventing the guide blades from being opened to such an extent that they can enter the turbine wheel.
However, disadvantages with the variable turbine geometries which are known from the prior art and have pins of this type are the resulting comparatively long tolerance chain with different manufacturing tolerances and the angular inaccuracy resulting therefrom in turn at the guide blades. In addition, the pin or, in general, the stop has to be placed in a separate component, for example in the blade carrier, thus resulting in further processing steps and therefore in a higher outlay on production and costs.
The present invention is therefore concerned with the problem of specifying, for a variable turbine geometry of the type in question, an improved or at least an alternative embodiment which in particular reduces the length of a tolerance chain and, in addition, can be realized cost-effectively.
This problem is solved according to the invention by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims.